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Strength of Coupling Bolts.
Moment of solid shaft = moment of hollow shaft

Let D = i.    Then d±= ^J
Weight of solid shaft

« -979
'9792

_
Weight of hollow shaft ~ 7r(R2

= 1-277 :

Example 18. — Find the relative strengths of shafts : —

2|" round,   3!" round,  3" square,* and 5" x 2" rectangular.

Moment of 2\" round  oc

~~

•1963 x 15*62 = 3*066  say 31.

3!"     »      a     „    = '1963 x 42*87 = 8.415   say 84.

3" square  oc -208 s5 =   '208 x 27      = 5*616   say 56.

5"x2"rect.   a    -2944 -r-^-^      =5-467   say 55.

Strength of Coupling Bolts.—Fig. 373 is the face view of

a flange coupling.   As the bolts and shaft must be equally strong:
and the allowable stress on the bolts = |/s (see p. 415)

Moment of bolts = moment of shaft

I

/. 844.)